One of the problems when baking with conventional baking pans of uniform thickness and insulating characteristics is that a product baked therein will have certain portions that will be heated more than other portions. This is especially true of certain portions of a product such as the side and edge portions, and it is also true of indentations and areas with sharply divergent contours and especially concave areas where heat will be trapped and will cause those portions of the product or cake being baked to heat more than other portions. This can result in excessive rise of the batter or dough especially near the center of a cake being baked and can give the cake a odd shape which is difficult to compensate for especially when the cake is overturned and is in condition to be iced or frosted. These problems are exacerbated when the products to be baked have shapes such as a contoured shape of a character, a face, or some other three dimensional shape or design. With the present pan construction having portions of different thickness and insulating characteristics those portions with the greatest insulation will slow down or reduce the heat transferred to the corresponding areas of the batter/dough and consequently will slow the speed of cooking or baking in those areas resulting in a more uniform heat distribution in the product as it is baked. In the past, various types of insulating inserts, of metallic or other materials, laminated structures, and other means have been used for this purpose. Such means have been positioned on or in the baking pan itself in order to slow down the baking in certain portions more than in others. One such device is disclosed in Kaufman U.S. Pat. No. 3,612,036. This and other prior art devices, however, have not resulted in uniformly baked products throughout, they have not eliminated the problem of "center rise", and such means have not generally been adopted by the industry or by baking pans used for home baking. Such known constructions have also been expensive to construct, and their use has been limited to certain types of products and therefore they have not had general usage for baking products of a particular size or shape.
In the current market, it is often necessary to design a baking pan that is suitable for use in a microwave oven as well as in a conventional baking oven. To meet these requirements means that baking pans must not be made of metal because metals are not transparent to microwave energy and might damage the oven if positioned in a microwave oven. It is also desirable to be able to develop a baking pan which has the desirable characteristics set forth above that can also be made relatively cheaply and be able to be mass produced so that they can be used in conventional baking ovens as well as in microwave ovens. It is also desired when selling prepackaged baking products to be baked to be able to include a disposable baking pan and especially one that is suitable for use in both types of ovens. For many such uses, a disposable pan formed of a relatively thin plastic material that is not damaged at the usual cooking temperature is supplied. In other instances a paper baking pan or a paper baking pan having a layer of plastic material applied to one or both surfaces thereof are used, but so far as known nobody provides such a baking pan which has different thickness or insulated portions. Relatively thin plastic baking pans that have uniform thickness throughout are not altogether satisfactory because they do not provide uniform baking of the dough and may actually accentuate the problems produced by uneven temperature distribution especially when they are used in relatively rapid baking procedures. This problem is further exacerbated if the pan has a sculptured pattern formed in the surface thereof which is the surface that becomes the top surface of the baked product. Consequently, uneven rising of the baking dough with portions being overbaked and portions being underbaked results. These conditions can also produce an objectionable crown near the center of the top of the dough as it is baking thereby adding to the distortion of the finished product. These effects are undesirable in most baked products and are especially objectionable in products such as cakes including layered cakes where it is desired to produce a certain shape before the icing or frosting is applied. The problems described will be accentuated in cakes formed of mulitiple layers wherein each of the different layers is baked in a separate pan and vertically assembled during the icing or frosting operation.
It is becoming popular to bake cakes with distinctive profiles on their upper surfaces such as the profile of a distinctive design character or other sculptured shape. The shape that is desired is produced as a result of the shape of the bottom of the pan in which it is baked. Once the product has been baked and cooled the pan is overturned so that the baked product will fall out of the pan and have its sculptured surface appear as the upper surface of the cake. If the sculptured shape of the pan has inwardly or outwardly sharply protruding regions these regions being thinner will be baked and dried more than other areas of the batter or dough. In order to make the batter/dough cook uniformly throughout, including throughout the sharply sculptured portions, the present invention teaches thickening the plastic or paper pan in the area of outwardly and inwardly protruding portions so that the protruding portions will be somewhat more insulated from the heat and therefore will receive about the same amount of baking as the rest of the product. If this is not done the protruding portions of the cake when it is overturned will be brittle and crumbly causing those design portions to break more easily adding to the difficulty of applying a uniform layer of icing or frosting to the cake. The breaking will also destroy the shape that is desired.